BACKGROUND: To evaluate the methodological quality of systematic reviews (SRs) or meta-analysis of trastuzumab-based therapy for breast cancer. METHODS: We searched the PubMed, EMBASE, Web of science, Cochrane library, international prospective register of systematic reviews, Chinese BioMedical Literature Database, Wan Fang, China National Knowledge Infrastructure and VIP database for SRs or meta-analysis. The methodological quality of included literatures was appraised by risk of bias in systematic review (ROBIS) tool. RESULTS: Twenty three eligible systematic reviews or meta-analysis were included. Only 2 systematic reviews provided protocol. The most frequently searched databases were PubMed, MEDLINE, EMBASE, and the Cochrane. The two-reviewers model described in the screening for eligible original articles, data extraction, and methodological quality evaluation had 30%, 61%, and 26%, respectively. In methodological quality assessment, 52% SRs or meta-analysis used the Jadad scoring or Cochrane reviewer' handbook. Research question were well matched to all SRs or meta-analysis in phase 1 and 35% of them evaluated "high" risk bias in study eligibility criteria. The "high" risk of bias in all non-Cochrane SRs or meta-analyses, which involve methods used to identify and/or select studies. And more than half SRs or meta-analysis had a high risk of bias in data collection and study appraisal. More than two-third of SRs or meta-analysis were accomplished with high risk of bias in the synthesis and findings. CONCLUSIONS: The study indicated poor methodological and reporting quality of SRs/meta-analysis assessing trastuzumab-based therapy for breast cancer. Registration or publishing the protocol and the reporting followed the PRISMA checklist are recommended in future research. Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.